This invention relates to a trim angle control device for marine propulsion motors and more particularly to an improved arrangement for controlling the trim position of a marine outboard drive.
It is well known to support a marine outboard drive (either an outboard motor or the outboard drive portion of an inboard/outboard unit) for pivotal movement about a horizontally extending tilt axis. This pivotal movement is employed for permitting the outboard drive to be tilted up out of the water when not in use or, alternatively, for adjustment of the trim position of the outboard drive during operation of the associated watercraft. It is also well known that the optimum trim angle of the outboard drive varies with the running condition of the watercraft. A wide variety of power units are employed for effecting the pivotal movement of the outboard drive to adjust its trim position during running. Many of these devices are purely manual and require the operator's attention to set the trim angle for the various running conditions. Other devices, which are completely automatic, have also been proposed. The manual devices have the disadvantage of requiring the operator's attention so as to set the trim angle and thus divert from his other duties. Automatic systems, on the other hand, tend to cause frequent hunting of the position of the outboard drive and will adjust its position to compensate for transitory conditions. As a result, these devices do not actually provide the optimum trim angle under all conditions, particularly during transition from one condition to another.
The automatic systems also have a further disadvantage. For example, there are many times when the desirable trim angle is independent of the actual running condition of the watercraft. For example, when traveling at slow speeds, the automatic systems generally cause the outboard drive to be tilted down. However, if the watercraft is being operated in shallow water at low speeds, such a tilted down condition of the outboard drive is not only unnecessary but may be dangerous. In addition, even in deep water, there may be times when the operator wishes to achieve a sudden tilting up of the outboard drive to avoid an object which may be floating in the water or only shallowly submerged.
It is, therefore, a principal object of this invention to provide a device for setting the trim angle of an outboard drive that is simple in operation and which does not require great attention from the operator.
It is a further object of this invention to provide a trim angle control device for a marine propulsion unit that is semi-automatic in operation so that the operator may select a preset trim condition but can easily override this condition or make other settings of the outboard drive as he chooses.